Various gases are dissolved in the circulatory blood system of living bodies. Changes in ambient pressure can lead to dispersion of gas bubbles from the liquid. At slow pressure changes, the body can expel the bubbles. However at a high rate of change the body cannot expel them fast enough and they can accumulate or grow. Detection of gas bubbles in a living body, at an early stage of accumulating would allow treatment before it is too late.
As an example, people moving quickly from a place of high atmospheric pressure to low atmospheric pressure, would be interested in accurate monitoring of their situation in order to safely control the rate of change. For example, underwater divers use statistical tables to determine the rate at which they can surface from a deep dive instead of measuring their actual physical state. While devices have been described for detection of bubbles in blood, for example in U.S. Pat. No. 6,261,233, the disclosure of which is incorporated herein by reference, which describes an ultrasound system, such devices have apparently not found actual use, especially in underwater situations.